JP5841691B2 - Light source device and endoscope device - Google Patents

Description

  The present invention relates to a light source device and an endoscope device suitable for an endoscope.

  2. Description of the Related Art Conventionally, endoscopes in which a long and narrow endoscope is inserted into a body cavity or the like to observe a test site and perform various treatments have been widely used. In such an endoscope, a light source device is employed to perform imaging inside the cavity. In recent years, a light source device employing a semiconductor light source such as an LED as a light emitting unit may be used. Such a light source device can perform dimming control of the LED by PWM control that changes the duty ratio of the drive pulse or current control that changes the LED current.

  A light source device using such an LED light source generates heat in accordance with the amount of light emission, and the amount of light varies depending on the temperature change during the heat generation. Japanese Patent Application Publication No. 2007-149469 (hereinafter referred to as Document 1) discloses an apparatus for cooling an LED using a Peltier element. The device of Literature 1 drives the Peltier device with a periodic pulse current that rises earlier than the rise of the pulse current of the LED drive current, thereby enabling cooling following the heat generation of the pulsed LED. ing.

  However, the LED light source in the proposal of Document 1 is used for a direct-view display device or projector, and the light amount change is relatively small. On the other hand, in the light source employed in the endoscope, the change in the amount of illumination light is relatively large depending on the observation mode, and the change in the heat generation amount of the LED light source is also relatively large. For this reason, even if the proposal of literature 1 is adopted, cooling control following the temperature change of the LED light source cannot be performed, and the life of the LED is adversely affected due to insufficient cooling, or condensation occurs due to overcooling. There was a problem that there was.

  An object of the present invention is to provide a light source device and an endoscope device that can perform cooling excellent in followability to a temperature change even when a light amount change and a temperature change are relatively large.

A light source device of one embodiment according to the present invention includes a semiconductor light emitting device, the semiconductor light-emitting element and a coolable configured cooling element, wherein the semiconductor light emitting element drive signal for emitting the light to the semiconductor light emitting device semiconductor a semiconductor light emitting element driving unit supplies to the light emitting element, and the cooling element to the semiconductor light emitting element cooling device driver for supplying a cooling element drive signal to the cooling device for cooling the duty of the semiconductor light emitting element driving signal a semiconductor light emitting element drive control section for controlling the light emission amount of the semiconductor light emitting element by setting the ratio, the semiconductor and the temperature sensor for measuring the temperature of the light emitting element, set the semiconductor light emitting by the semiconductor light emitting element drive controller It has the same duty ratio as the duty ratio of the element driving signal, and the cooling element with a timing synchronized with the semiconductor light emitting element driving signal It controls the cooling device driving unit so as to generate a driving signal, cooling on the basis of the measurement result of the temperature sensor, the signal level of the cooling element drive signal for controlling the cooling device driving unit so as to be adjusted An element drive control unit.

An endoscope apparatus according to an aspect of the present invention includes an endoscope, a semiconductor light emitting element that generates illumination light to be supplied to the endoscope, and a cooling element configured to be capable of cooling the semiconductor light emitting element. When a semiconductor light emitting element driving unit for supplying a semiconductor light-emitting element driving signal to the semiconductor light emitting element for emitting the light to the semiconductor light emitting element, a cooling element drive signals for cooling the semiconductor light emitting element to the cooling element A cooling element driving unit that supplies the cooling element to the cooling element, a semiconductor light emitting element driving control unit that controls a light emission amount of the semiconductor light emitting element by setting a duty ratio of the semiconductor light emitting element driving signal , and a temperature of the semiconductor light emitting element a temperature sensor for measuring the have the same duty ratio as the duty ratio of the set by the semiconductor light emitting element driving control unit the semiconductor light-emitting element driving signal, and the semiconductor Controls the cooling device driving unit so as to generate the cooling element drive signals having a timing synchronized with the optical element driving signal, based on a measurement result of the temperature sensor, the signal level of the cooling element drive signal adjustment a cooling element drive control section that controls the cooling device driving unit so as to comprise a.

The block diagram which shows the light source device which concerns on one embodiment of this invention. The flowchart for demonstrating the light control and cooling control of embodiment. 4 is an explanatory diagram for explaining a PWM pulse supplied to the R-LED 42 and a drive current supplied to the Peltier element 56. FIG. The figure which shows the structure of the LED light source which is hard to receive to the influence of dew condensation. The figure which shows the example of the other structure of the LED light source which is hard to receive to the influence of dew condensation. The figure which shows the example of the other structure of the LED light source which is hard to receive to the influence of dew condensation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a light source device according to an embodiment of the present invention. In the present embodiment, the light source device is applied to an endoscope system having an endoscope, a video processor, and a monitor.

  The endoscope system 1 includes an endoscope 10, a video processor 20, a monitor 30, and a light source device 40. The endoscope 10 has an elongated insertion portion 11 that can be inserted into a lumen or the like at the distal end side, and the proximal end side is detachably connected to the light source device 40 by a connector 12. ing.

  Further, the endoscope 10 is detachably connected to the video processor 20 by a cable 17 and a connector 18. Thus, different types of endoscopes can be attached to the light source device 40 and the video processor 20.

  At the distal end of the insertion portion 11, an imaging element 13 for capturing an image of a subject such as in a lumen and a lens 14 for irradiating the subject with light from the light source device 40 are disposed. The illumination light transmitted from the light source device 40 via the light guide 15 is irradiated to the subject by the lens 14. The imaging element 13 is configured by a CCD, a CMOS sensor, or the like. Return light from the subject is incident on the imaging surface, photoelectrically converts the incident subject optical image, and sequentially outputs imaging outputs based on the accumulated charges.

  The image pickup device 13 operates by receiving a drive signal including a synchronization signal from the video processor 20, and supplies an image pickup output to the video processor 20 via the signal line 16.

  The video processor 20 performs predetermined signal processing on the imaging output to generate a video signal that can be displayed on the monitor 30. A video signal from the video processor 20 is supplied to the monitor 30 via the cable 21. In this way, an endoscopic image based on the imaging output can be displayed on the display screen of the monitor 30.

  In addition, the video processor 20 can control the light source device 40 so that the brightness of the captured image becomes the target brightness. The video processor 20 outputs information on the ratio between the brightness obtained from the captured image and the target brightness to the light source device 40 as brightness control information. The brightness control information is supplied to the control unit 41 of the light source device 40 via the cable 22.

  The light source device 40 includes an LED (R-LED) 42 that generates red light, an LED (G-LED) 43 that generates green light, an LED (B-LED) 44 that generates blue light, and an LED that generates purple light. (V-LED) 45 is included. In this embodiment, an example in which LEDs that generate four colors of light are employed will be described. However, the types and the number of colors are not limited to those in this embodiment. For example, FIG. An LED that generates color (amber) light may be added.

  Lenses 42a to 45a are arranged on the optical axes of the emitted lights of the LEDs 42 to 45, respectively. Each of the lenses 42a to 45a converts the light emitted from the LEDs 42 to 45 into substantially parallel light and emits the light. On the optical axis of the lens 42a that emits light from the R-LED 42, dichroic filters 47 to 49 constituting an optical path portion are arranged. Light from the G-LED 43 is also incident on the dichroic filter 47 via the lens 43a. The light from the B-LED 44 is also incident on the dichroic filter 48 via the lens 44a, and the light from the V-LED 45 is also incident on the dichroic filter 49 via the lens 45a.

  The dichroic filter 47 reflects the light from the G-LED 43 and transmits the light from the R-LED 42. The dichroic filter 48 reflects the light from the B-LED 44 and transmits the light transmitted through the dichroic filter 47. The dichroic filter 49 reflects the light from the V-LED 45 and transmits the light transmitted through the dichroic filter 48.

  Thus, the light from the LEDs 42 to 45 is synthesized by the dichroic filters 47 to 49. The combined light from the dichroic filter 49 is incident on the light guide 15 via the lens 50. It is possible to change the arrangement order of the LEDs 42 to 45 by appropriately setting the characteristics of the dichroic filters 47 to 49, but the characteristic of the dichroic filter is that the LEDs 42 to 45 are arranged in the wavelength band of the emitted light. Is easy to set.

  Each of the LEDs 42 to 45 is driven by the LED driving unit 46 to light up. The LED drive unit 46 is controlled by the control unit 41 to generate a PWM pulse that is a drive signal for driving each LED. Each of the LEDs 42 to 45 emits light with a light emission amount corresponding to the duty ratio and current amount of the PWM pulse from the LED drive unit 46. The control unit 41 outputs dimming information for controlling each of the LEDs 42 to 45 to the LED driving unit 46, thereby controlling the duty ratio of the PWM pulse and dimming control of each of the LEDs 42 to 45.

  The control unit 41 generates dimming information so that the light emission amounts of the LEDs 42 to 45 can maintain a predetermined color balance. The color balance of each of the LEDs 42 to 45 needs to be determined by the spectral sensitivity characteristics of the endoscope 10. The memory unit 51 of the light source device 40 stores information on the light amount ratios generated by the LEDs 42 to 45 in accordance with the spectral sensitivity characteristics of the endoscope 10 in order to obtain an optimum color balance. The control unit 41 outputs control information for controlling each of the LEDs 42 to 45 to the LED driving unit 46 based on the information on the light amount ratio stored in the memory unit 51.

  In addition, although the memory part 51 demonstrated as what has memorize | stored the information of the light quantity ratio of each LED for obtaining the optimal color balance, attaching the endoscope 10 to the video processor 20 or the light source device 40 is demonstrated. Thus, information regarding the light amount ratio may be read from the endoscope 10 and set in the control unit 41.

  In order to obtain an optimal color balance, information on the light amount ratio of each LED may be input to the control unit 41, and the memory unit 51 is not necessarily provided. The light source device 40 is provided with an operation panel 52, and the operation panel 52 can output a signal based on a user operation to the control unit 41. By using this operation panel 52, it is also possible to input light quantity ratio information. The operation panel 52 is provided with a display unit (not shown) so that the current set value and the like can be displayed.

  Based on the brightness control information from the video processor 20, the control unit 41 controls the light amount of each of the LEDs 42 to 45 while maintaining a light amount ratio that provides an optimal color balance. For example, dimming information corresponding to the light amount value of the G-LED 43 to be set according to the brightness control information is stored in the memory unit 51, and the control unit 41 stores the memory unit 51 based on the brightness control information. The light control information for controlling the G-LED 43 can be acquired by reading the light control information stored in the. Further, the control unit 41 can obtain the dimming information of the other LEDs 42, 44, 45 based on the information on the light amount ratio stored in the memory unit 51.

  The dimming information obtained by the control unit 41 is for controlling the duty ratio of PWM pulses supplied to the LEDs 42 to 45. The LED driving unit 46 generates a PWM pulse having a duty ratio specified by the dimming information and supplies the PWM pulse to each of the LEDs 42 to 45. Thereby, each LED42-45 is pulse-driven by the duty ratio based on brightness control information and a light quantity ratio, and light-emits by desired brightness.

  In the present embodiment, a Peltier element 56 that is a thermoelectric conversion element is attached to the R-LED 42 for cooling. The R-LED 42 includes a substrate (not shown) and a light emitting unit disposed on the substrate. For example, a Peltier element 56 is disposed on the back side of the substrate. The Peltier element 56 is a cooling member that utilizes heat absorption and heat dissipation caused by the current flowing through the pn junction, and cools the R-LED 42 by bringing the cooling surface of the Peltier element 56 into contact with the back surface of the substrate of the R-LED 42. It is supposed to be.

  The cooling effect of the Peltier element 56 is controlled by the current value of the drive current flowing through the Peltier element 56. The Peltier drive unit 55 is controlled by the control unit 41 to control the current value of the drive current that flows through the Peltier element 56, thereby controlling the cooling of the R-LED 42.

  In the present embodiment, the control unit 41 controls the Peltier drive unit 55 so that a current that is in synchronization with the duty ratio of the PWM pulse that drives the R-LED 42 and that is synchronized with the PWM pulse flows to the Peltier element 56. Output a signal. That is, the Peltier element 56 exhibits a cooling effect when a drive current flows during a period in which a pulsed LED current flows through the R-LED 42. Thus, in the present embodiment, since the driving of the R-LED 42 and the driving of the Peltier element are completely synchronized, cooling by the Peltier element 56 is performed during the period in which the R-LED 42 is lit and generates heat. Therefore, the temperature rise by light emission of R-LED42 can be suppressed.

  However, in endoscope illumination applications, the amount of light emitted from the R-LED 42 varies significantly depending on the observation mode and the like. For this reason, the case where the cooling effect by the Peltier element 56 is not sufficient, or the case where it cools too much may arise.

  Therefore, in the present embodiment, the actual temperature is measured, and the current value of the drive current of the Peltier element 56 is controlled based on the measurement result. The light source device 40 is provided with thermistors 53 and 54. The thermistor 53 is disposed in the vicinity of the R-LED 42, measures the temperature in the vicinity of the R-LED 42, and outputs the measurement result to the control unit 41. The thermistor 54 is disposed at an appropriate position in the housing of the light source device 40, measures the temperature in the housing (room temperature), and outputs the measurement result to the control unit 41.

  The control unit 41 receives temperature measurement results from the thermistors 53 and 54, and controls the current value of the drive current of the Peltier element 56 in accordance with the temperature measurement results. For example, the control unit 41 controls to increase the current value of the drive current of the Peltier element 56 as the temperature in the vicinity of the R-LED 42 from the thermistor 53 increases, and to decrease the current value of the drive current as the temperature decreases. . For example, the control unit 41 may control the drive current of the Peltier element 56 using the temperature measurement result of the thermistor 54. For example, the control unit 41 may control the drive current of the Peltier element 56 so that the temperature in the vicinity of the R-LED 42 is not lower than the room temperature obtained by the thermistor 54.

  Note that the light amount of the R-LED 42 fluctuates relatively greatly depending on the temperature of the junction (semiconductor pn junction), and the light amount is significantly reduced at a high temperature. For this reason, in order to secure a sufficient amount of light as red, it is necessary to cool the R-LED 42 to near the dew point temperature. In this way, the R-LED 42 is more susceptible to temperature than the other color LEDs 43 to 45 and needs to be sufficiently cooled. For this reason, in this Embodiment, although the example which arrange | positions the Peltier element 56 only to R-LED42 was shown, you may make it provide a Peltier element in all or one part of other LED43-45. Is clear. Even in this case, the drive current is made to flow through each Peltier element in complete synchronization with the drive pulse for driving each LED, and each Peltier is based on the temperature measurement result of the thermistor arranged in the vicinity of each LED, the temperature in the housing, and the like. The current value of the drive current supplied to the element is determined.

  Next, the operation of the embodiment configured as described above will be described with reference to FIGS. FIG. 2 is a flowchart for explaining dimming and cooling control according to the embodiment. FIG. 3 is an explanatory diagram for explaining the PWM pulse supplied to the R-LED 42 and the drive current supplied to the Peltier element 56.

  When the power source of the light source device 40 is turned on, the control unit 41 acquires information on the light amount ratio from the memory unit 51 (step S1). In step S2, the control unit 41 acquires brightness control information from the video processor 20. The control unit 41 accesses the memory unit 51 based on the brightness control information, obtains a control value (duty ratio) for controlling the reference G-LED 43, and further determines other LED 42, The duty ratios 44 and 45 are calculated (step S4).

  The control part 41 produces | generates the light control information for designating the duty ratio calculated | required about each LED42-45 (step S4), and outputs it to the LED drive part 46 (step S5). The LED driving unit 46 generates a PWM pulse having a duty ratio based on the dimming information and supplies the PWM pulse to each of the LEDs 42 to 45. Thereby, LED42-45 generate | occur | produces the light of the light quantity based on light control information. Light emitted from the LEDs 42 to 45 is synthesized by the dichroic filters 47 to 49 and enters the light guide 15 through the lens 50 as illumination light. The illumination light transmitted through the light guide 15 is irradiated to the subject from the lens 14.

  The imaging element 13 receives reflected light from the subject and performs photoelectric conversion to obtain a captured image. This captured image is supplied to the video processor 20 via the signal line 16. The video processor 20 performs predetermined signal processing on the captured image to generate a video signal, and supplies the video signal to the monitor 30 via the cable 21. Thus, the endoscopic image is displayed on the display screen of the monitor 30.

  Further, the video processor 20 generates brightness control information by comparing the brightness of the captured image with the target brightness. For example, the video processor 20 generates brightness control information for each field and outputs the brightness control information to the control unit 41 of the light source device 40.

  Thus, the control unit 41 generates dimming information based on the brightness control information for each field, for example, so that the amount of illumination light by the combined light emitted from the LEDs 42 to 45 reaches the target brightness. Take control.

  Moreover, the control part 41 acquires the temperature of the vicinity of R-LED42, and the temperature in a housing | casing from the thermistors 53 and 54 in step S6. The control unit 41 generates a drive current having the same duty ratio synchronized with the rise and fall of the PWM pulse supplied to the R-LED 42 and having a current value corresponding to the temperature acquired in step S6. A control signal is generated and output to the Peltier drive unit 55 (step S7).

  The Peltier drive unit 55 is controlled by a control signal from the control unit 41 to generate a drive current for the Peltier element 56. This drive current flows to the Peltier element 56, and the cooling surface of the Peltier element 56 is cooled. For example, as in the example of FIG. 2, the control unit 41 may acquire the temperature at the same cycle as the generation cycle of the brightness control information and generate the control signal. In this case, the control unit 41 generates a control signal for controlling the drive current based on the temperature acquired for each field, for example, so that the temperature in the vicinity of the R-LED 42 reaches a predetermined target temperature. To control.

  A symbol IL in FIG. 3 indicates a PWM pulse supplied to the R-LED 42, and a symbol IP indicates a drive current. As shown in FIG. 3, the drive current is synchronized with the PWM pulse, and the drive current flows through the Peltier element 56 during the period when the LED current flows through the R-LED 42, that is, during the same period as the light emission period of the R-LED 42. Thus, when the R-LED 42 emits light and tries to generate heat, it is cooled by the Peltier element 56. Furthermore, the current value of the drive current changes according to the temperature of the thermistors 53 and 54, and the temperature in the vicinity of the R-LED 42 can be maintained substantially constant.

  In the example of FIG. 3, when the duty ratio of the PWM pulse supplied to the R-LED 42 is reduced and the amount of light emission is reduced and the temperature in the vicinity of the R-LED 42 is lowered, the driving current is also lowered and the cooling effect is suppressed. In addition, the temperature in the vicinity of the R-LED 42 is maintained substantially constant.

  For example, when the observation scene by the endoscope 10 changes from a far point to a near point, the light amount of the R-LED 42 is rapidly decreased and the heat generation amount is also rapidly decreased by the brightness control by the control unit 41. Even in this case, the drive current of the Peltier element 56 is generated in synchronization with the PWM pulse of the R-LED 42, and the current value of the drive current rapidly decreases according to the measurement results of the thermistors 53, 54. It can prevent that the cooling effect of the element 56 falls and the temperature of R-LED42 vicinity becomes low too much. Thereby, generation | occurrence | production of the dew condensation by overcooling of LED can be prevented.

  On the contrary, when the observation scene by the endoscope 10 changes from the near point to the far point, the amount of heat generation increases rapidly as the LED light amount increases. Even in this case, since the current value of the drive current increases rapidly according to the measurement results of the thermistors 53 and 54, the cooling effect of the Peltier element 56 is rapidly increased and the temperature in the vicinity of the R-LED 42 becomes too high. This can be prevented.

  As described above, in the present embodiment, a current is supplied to the Peltier element for cooling the corresponding LED at a timing coincident with the drive pulse of the LED, and each Peltier element is based on the temperature in the vicinity of each LED or the temperature in the housing. The current value of the driving current is determined. As a result, cooling by the Peltier element is performed during the light emission period of the LED, and the cooling effect of the Peltier element is controlled based on the temperature in the vicinity of each LED and the temperature in the housing, so that each LED has an appropriate temperature. Cooling control is possible. Thereby, even when the light quantity change and the temperature change are relatively large, it is possible to perform cooling with excellent followability to the temperature change.

  By the way, in a high humidity environment, the dew point temperature is relatively high and dew condensation is likely to occur. For example, when the humidity is about 85 RH%, the surface of the LED is easily brought to the dew point temperature or less, and condensation tends to occur. If condensation occurs on the surface of the LED, the amount of emitted light is likely to decrease or cause a failure. Therefore, a structure that is not easily affected by condensation is adopted as the structure of the LED light source.

(First example)
FIG. 4 shows the structure of an LED light source that is hardly affected by dew condensation. FIG. 4 (a) is a side view and FIG. 4 (b) is a plan view. In FIG. 4, the direction of gravity is indicated by an arrow. LED61 has the light emission part 61a arrange | positioned on the front surface of the board | substrate 61b and the board | substrate 61b. A Peltier element 63 (shaded portion) is disposed on the back side of the substrate 61b of the LED 61 via a heat diffusion plate 62. The Peltier element 63 is disposed on the heat sink 64, and the cooling surface (upper surface and side surface) 63 a side is covered with a heat diffusion plate 62. That is, the cooling surface 63 a of the Peltier element 63 is in contact with the heat diffusion plate 62, and the heat dissipation surface (bottom surface) 63 b is in contact with the heat sink 64.

  By passing a drive current through the Peltier element 63, heat is transmitted from the cooling surface 63a of the Peltier element 63 to the heat radiation surface 63b, and the cooling surface 63a is cooled. The heat generated in the LED substrate 61b is transmitted to the cooling surface 63a of the Peltier element 63 cooled via the heat diffusion plate 62 on the back surface of the substrate 61b, and further transmitted from the heat dissipation surface 63b of the Peltier element 63 to the heat sink 64. Heat is dissipated. Thereby, the temperature of LED61 can be reduced.

  The heat sink 64 is provided with a sealing member 66 that surrounds the Peltier element 63, the heat diffusion plate 62, and the LED 61 disposed on the heat sink 64 and constitutes a sealed region 65. The sealing member 66 has a lens portion 66 a at a position facing the light emitting portion 61 a of the LED 61, and can emit light from the light emitting portion 61 a to the outside of the sealed region 65. The sealing member 66 may be made of a transparent member, and the lens portion 66a may be omitted.

  In the example of FIG. 4, the thermal diffusion plate 62 is not covered in a partial region below the gravity direction of the Peltier element 63, and the cooling surface 63a is exposed in the sealed region 65 in the partial region and is in the atmosphere. An exposed surface 67 is configured.

  In the LED light source configured as described above, the LED substrate 61b is cooled by passing a driving current through the Peltier element 63. The Peltier element 63 cools the LED substrate 61b through the heat diffusion plate 62, and the temperature of the LED substrate 61b is higher than the cooling surface 63a of the Peltier element 63. Therefore, when the Peltier element 63 is driven, the air exposure surface 67 that is a part of the cooling surface 63a of the Peltier element 63 is at a lower temperature than the LED substrate 61b.

  In the sealed region 65, dew condensation first occurs at a portion where the surface temperature is equal to or lower than the dew point temperature, and water droplets generated by the dew condensation gather at this dew condensation occurrence position. In the example of FIG. 4, when the Peltier element 63 is driven, the cooling surface 63 a has the lowest temperature in the sealed region 65. Therefore, when condensation occurs, first, water droplets (shaded portions and meshed portions) 68 are formed on the air exposure surface 67 due to condensation. Further, since condensation occurs on the air exposure surface 67, most of the total water amount in the sealed region 65 is collected in the vicinity of the air exposure surface 67, so that the humidity in the sealed region 65 decreases. As a result, the dew point temperature is lowered in the sealed region 65, condensation is extremely difficult to occur in portions other than the air exposed surface 67, and condensation does not occur in the LED 61 portion.

  Further, since the air exposure surface 67 is located on the lowest side in the direction of gravity in the sealed region 65, the water droplets 68 collected in this portion are difficult to move to other portions. As a result, it is possible to reliably prevent water droplets due to condensation from adhering to the LED 61.

  It is conceivable to employ a high heat resistance member as the heat diffusion plate 62. In this case, the temperature difference between the cooling surface 63a and the LED substrate 61b is further increased. That is, the temperature of the air exposure surface 67 is further lower than the temperature of the LED 61. As a result, condensation is more likely to occur in the vicinity of the air-exposed surface 67, and it is possible to further prevent condensation from occurring in the LED 61.

(Second example)
FIG. 5 shows an example of another structure of the LED light source that is not easily affected by dew condensation. FIG. 5 (a) is a side view and FIG. 5 (b) is a plan view. Also in FIG. 5, the direction of gravity is indicated by an arrow. LED61 has the light emission part 61a arrange | positioned on the front surface of the board | substrate 61b and the board | substrate 61b. A Peltier element 73 (shaded portion) is disposed on the back side of the substrate 61b of the LED 61 via a heat diffusion plate 72. The Peltier element 73 is disposed on the heat sink 75, and the cooling surface (upper surface and side surface) 73 a side is covered with a heat diffusion plate 72. That is, the cooling surface 73 a of the Peltier element 73 is in contact with the heat diffusion plate 72, and the heat dissipation surface (bottom surface) 73 b is in contact with the heat sink 75.

  By passing a drive current through the Peltier element 73, heat is transmitted from the cooling surface 73a of the Peltier element 73 to the heat dissipation surface 73b, and the cooling surface 73a is cooled. The heat generated in the LED substrate 61b is transmitted to the cooling surface 73a of the Peltier element 73 cooled via the heat diffusion plate 72 on the back surface of the substrate 61b, and further transmitted from the heat dissipation surface 73b of the Peltier element 73 to the heat sink 75. Heat is dissipated. Thereby, the temperature of LED61 can be reduced.

  Further, on the heat sink 75, a sealing member 77 constituting a sealed region 76 is provided so as to surround the Peltier element 73, the heat diffusion plate 72, and the LED 61 disposed on the heat sink 75. The sealing member 77 has a lens part 77 a at a position facing the light emitting part 61 a of the LED 61, and can emit light from the light emitting part 61 a to the outside of the sealed region 76. The sealing member 77 may be made of a transparent member, and the lens portion 77a may be omitted.

  In the example of FIG. 5, in a partial region below the gravity direction in the sealed region 76, the Peltier element 74 that forms the air exposed surface 78 by exposing the cooling surface (upper surface and side surface) in the sealed region 76. Is arranged. The heat dissipation surface (bottom surface) of the Peltier element 74 is in contact with the heat sink 75.

  In the LED light source configured in this way, the LED substrate 61b is cooled by passing a drive current through the Peltier element 73. Further, the cooling surface of the Peltier element 74 is cooled by passing a drive current through the Peltier element 74. The Peltier element 73 cools the LED substrate 61b through the heat diffusion plate 72, and the temperature of the LED substrate 61b is higher than the cooling surface 73a of the Peltier element 73. Therefore, if the cooling effect of the Peltier element 74 is equal to or greater than the cooling effect of the Peltier element 73, the air exposure surface 78 that is the cooling surface of the Peltier element 74 is lower than the LED substrate 61b when the Peltier elements 73 and 74 are driven. It is temperature.

  In the sealed region 76, dew condensation first occurs at a portion where the surface temperature is equal to or lower than the dew point temperature, and water droplets generated by the dew condensation collect at this dew condensation occurrence position. Therefore, in the example of FIG. 5, when condensation occurs, first, water droplets (shaded portions and mesh portions) 79 due to condensation occur on the air exposure surface 78. Further, since condensation occurs on the air exposure surface 78, most of the total water content in the sealed region 76 is collected in the vicinity of the air exposure surface 78, so that the humidity in the sealed region 76 decreases. As a result, in the sealed region 76, condensation is extremely difficult to occur in portions other than the air exposure surface 78, and no condensation occurs in the LED 61 portion.

  Further, since the air exposure surface 78 is located on the lowest side in the gravitational direction in the sealed region 76, the water droplets 79 collected in this portion are difficult to move to other portions. As a result, it is possible to reliably prevent water droplets due to condensation from adhering to the LED 61.

(Third example)
FIG. 6 shows an example of another structure of the LED light source that is not easily affected by dew condensation. FIG. 6 (a) is a side view and FIG. 6 (b) is a plan view. Also in FIG. 6, the direction of gravity is indicated by an arrow. The third example is different from the second example of FIG. 5 only in that a temperature and humidity sensor 81 is provided. The temperature and humidity sensor 81 can measure the temperature and humidity near the LED 61. The measurement result of the temperature and humidity sensor 81 is supplied to a control unit (not shown) that drives and controls the Peltier elements 73 and 74. This control unit drives only the Peltier element 73 in the initial state.

  A control part calculates | requires dew point temperature from the temperature and humidity of a measurement result, and determines whether the temperature of LED61 vicinity is going to become below dew point temperature. The control unit drives the Peltier element 74 only when the temperature near the LED 61 is about to reach the dew point temperature or lower. As a result, the portion of the air exposed surface 78 of the Peltier element 74 first becomes the dew point temperature or lower, and condensation occurs on the air exposed surface 78. Thereby, generation | occurrence | production of the dew condensation in LED61 can be prevented.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, you may delete some components of all the components shown by embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

[Appendix]
1.
A semiconductor light emitting device;
A cooling element for cooling the semiconductor light emitting element having a temperature-controlled cooling surface;
The cooling surface is provided so as to cover the cooling surface other than the lower portion of the cooling element in the gravity direction, and heat generated in the semiconductor light emitting element is interposed between the semiconductor light emitting element and the cooling element. A heat diffusing member that conducts to
A light source device comprising: the semiconductor light emitting element, the cooling element, and a sealing member that houses the heat diffusion member in an airtight space.

2.
A semiconductor light emitting device;
A first cooling element that has a first cooling surface that is temperature controlled and cools the semiconductor light emitting element;
It is provided so as to cover the first cooling surface, and is conducted between the semiconductor light emitting element and the first cooling element, and conducts heat generated in the semiconductor light emitting element to the first cooling surface. A heat diffusion member;
The semiconductor light emitting element, the first cooling element, and a sealing member that houses the heat diffusion member in an airtight space, and a second cooling surface that is temperature-controlled, and the gravity of the semiconductor light emitting element in the airtight space A second cooling element that is disposed on the lower side in the direction and cools the airtight space by the second cooling surface;
A light source device comprising:

This application is filed on the basis of the priority claim of Japanese Patent Application No. 2013-173570 filed in Japan on August 23, 2013. It shall be cited in the drawing.

Claims (6)

A semiconductor light emitting device ;
A cooling element configured to be capable of cooling the semiconductor light emitting element ;
A semiconductor light emitting element driving unit for supplying a semiconductor light emitting element drive signal for emitting the light to the semiconductor light emitting element to the semiconductor light emitting element,
A cooling element driver for supplying to the cooling element cooling element drive signals for cooling the semiconductor light emitting element to the cooling element,
A semiconductor light emitting element drive control unit configured to control a light emission amount of the semiconductor light emitting element by setting a duty ratio of the semiconductor light emitting element drive signal ;
A temperature sensor for measuring the temperature of the semiconductor light emitting element ;
Generating the cooling element driving signal having the same duty ratio as the duty ratio of the semiconductor light emitting element driving signal set by the semiconductor light emitting element driving control unit and having a timing synchronized with the semiconductor light emitting element driving signal ; the controls the cooling element driving unit, and on the basis of the measurement result of the temperature sensor, the signal level of the cooling element drive signal for controlling the cooling device driving unit so as to adjust the cooling element drive control section, the
A light source device comprising: The light source device according to claim 1, wherein the cooling element drive control unit adjusts a signal level of the cooling element drive signal so that a measurement result of the temperature sensor is within a predetermined temperature range. A room temperature sensor for measuring room temperature,
The light source device according to claim 1, wherein the cooling element drive control unit adjusts a signal level of the cooling element drive signal based on measurement results of the temperature sensor and the room temperature sensor. The said cooling element drive control part adjusts the signal level of the said cooling element drive signal so that the measurement result of the said temperature sensor may become higher than the measurement result of the said room temperature sensor. Light source device.   An endoscope,
  A semiconductor light emitting element for generating illumination light to be supplied to the endoscope;
  A cooling element configured to be capable of cooling the semiconductor light emitting element;
  A semiconductor light emitting element driving unit for supplying a semiconductor light emitting element driving signal for causing the semiconductor light emitting element to emit light;
  A cooling element driving unit that supplies the cooling element with a cooling element driving signal for causing the cooling element to cool the semiconductor light emitting element;
  A semiconductor light emitting element drive control unit configured to control a light emission amount of the semiconductor light emitting element by setting a duty ratio of the semiconductor light emitting element drive signal;
  A temperature sensor for measuring the temperature of the semiconductor light emitting element;
  Generating the cooling element driving signal having the same duty ratio as the duty ratio of the semiconductor light emitting element driving signal set by the semiconductor light emitting element driving control unit and having a timing synchronized with the semiconductor light emitting element driving signal; A cooling element driving control unit that controls the cooling element driving unit so that a signal level of the cooling element driving signal is adjusted based on a measurement result of the temperature sensor.
  An endoscope apparatus characterized by comprising:   The semiconductor light emitting element drive control unit performs predetermined signal processing on the imaging output from the endoscope to generate a video signal, and sets the brightness of the image based on the video signal to a target brightness. Video processor for controlling the light emission amount of the semiconductor light emitting device by controlling
  The endoscope apparatus according to claim 5, further comprising:

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